I still have Internet Explorer 8 but every boot up Mr. Gates asks me to upgrade to IE9. I keep declining. Should I upgrade? How will it differ?
You should definitely upgrade. I cannot tell you how it will differ in terms of user experience (I suspect reasonably little, frankly speaking if you are using internet explorer then even if there are enhancements you wouldn’t notice them) but from a security point of view you owe it to your computer not to be exposing it to various threats that will over time be exposed in IE 8, while patched in IE 9.
Why do you keep declining? Generally speaking, it is much safer to keep your software up to date (upgrades usually plug holes that malware could exploit), and the chances are good that it will give you better performance too.
Probably not much: Release Notes for Internet Explorer 9 | Microsoft Learn
It’s smoother, faster, more stable and more similar to Chrome. I’ve been using both IE9 and Chrome for the past six months or so, usually at the same time, and I couldn’t tell you which is better.
Yes, update it if you’re running Windows Vista or 7. IE 9 won’t run on XP.